//package io.github.wycst.wast.common.tools;
//
//import java.io.FilterOutputStream;
//import java.io.IOException;
//import java.io.InputStream;
//import java.io.OutputStream;
//import java.nio.ByteBuffer;
//import java.nio.charset.Charset;
//import java.util.Arrays;
//
///**
// * This class consists exclusively of static methods for obtaining
// * encoders and decoders for the Base64 encoding scheme. The
// * implementation of this class supports the following types of Base64
// * as specified in
// * <a href="http://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a> and
// * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>.
// *
// * <ul>
// * <li><a name="basic"><b>Basic</b></a>
// * <p> Uses "The Base64 Alphabet" as specified in Table 1 of
// * RFC 4648 and RFC 2045 for encoding and decoding operation.
// * The encoder does not add any line feed (line separator)
// * character. The decoder rejects data that contains characters
// * outside the base64 alphabet.</p></li>
// *
// * <li><a name="url"><b>URL and Filename safe</b></a>
// * <p> Uses the "URL and Filename safe Base64 Alphabet" as specified
// * in Table 2 of RFC 4648 for encoding and decoding. The
// * encoder does not add any line feed (line separator) character.
// * The decoder rejects data that contains characters outside the
// * base64 alphabet.</p></li>
// *
// * <li><a name="mime"><b>MIME</b></a>
// * <p> Uses the "The Base64 Alphabet" as specified in Table 1 of
// * RFC 2045 for encoding and decoding operation. The encoded output
// * must be represented in lines of no more than 76 characters each
// * and uses a carriage return {@code '\r'} followed immediately by
// * a linefeed {@code '\n'} as the line separator. No line separator
// * is added to the end of the encoded output. All line separators
// * or other characters not found in the base64 alphabet table are
// * ignored in decoding operation.</p></li>
// * </ul>
// *
// * <p> Unless otherwise noted, passing a {@code null} argument to a
// * method of this class will cause a {@link java.lang.NullPointerException
// * NullPointerException} to be thrown.
// *
// * @author Xueming Shen
// * @since 1.8
// */
//
//public class Base64 {
//
//    private Base64() {
//    }
//
//    public static Object requireNonNull(Object obj) {
//        if (obj == null)
//            throw new NullPointerException();
//        return obj;
//    }
//
//    /**
//     * Returns a {@link Base64.Encoder} that encodes using the
//     * <a href="#basic">Basic</a> type base64 encoding scheme.
//     *
//     * @return A Base64 encoder.
//     */
//    public static Base64.Encoder getEncoder() {
//        return Base64.Encoder.RFC4648;
//    }
//
//    /**
//     * Returns a {@link Base64.Encoder} that encodes using the
//     * <a href="#url">URL and Filename safe</a> type base64
//     * encoding scheme.
//     *
//     * @return A Base64 encoder.
//     */
//    public static Base64.Encoder getUrlEncoder() {
//        return Base64.Encoder.RFC4648_URLSAFE;
//    }
//
//    /**
//     * Returns a {@link Base64.Encoder} that encodes using the
//     * <a href="#mime">MIME</a> type base64 encoding scheme.
//     *
//     * @return A Base64 encoder.
//     */
//    public static Base64.Encoder getMimeEncoder() {
//        return Base64.Encoder.RFC2045;
//    }
//
//    /**
//     * Returns a {@link Base64.Encoder} that encodes using the
//     * <a href="#mime">MIME</a> type base64 encoding scheme
//     * with specified line length and line separators.
//     *
//     * @param lineLength    the length of each output line (rounded down to nearest multiple
//     *                      of 4). If {@code lineLength <= 0} the output will not be separated
//     *                      in lines
//     * @param lineSeparator the line separator for each output line
//     * @return A Base64 encoder.
//     * @throws IllegalArgumentException if {@code lineSeparator} includes any
//     *                                  character of "The Base64 Alphabet" as specified in Table 1 of
//     *                                  RFC 2045.
//     */
//    public static Base64.Encoder getMimeEncoder(int lineLength, byte[] lineSeparator) {
//        Base64.requireNonNull(lineSeparator);
//        int[] base64 = Base64.Decoder.fromBase64;
//        for (byte b : lineSeparator) {
//            if (base64[b & 0xff] != -1)
//                throw new IllegalArgumentException(
//                        "Illegal base64 line separator character 0x" + Integer.toString(b, 16));
//        }
//        if (lineLength <= 0) {
//            return Base64.Encoder.RFC4648;
//        }
//        return new Base64.Encoder(false, lineSeparator, lineLength >> 2 << 2, true);
//    }
//
//    /**
//     * Returns a {@link Base64.Decoder} that decodes using the
//     * <a href="#basic">Basic</a> type base64 encoding scheme.
//     *
//     * @return A Base64 decoder.
//     */
//    public static Base64.Decoder getDecoder() {
//        return Base64.Decoder.RFC4648;
//    }
//
//    /**
//     * Returns a {@link Base64.Decoder} that decodes using the
//     * <a href="#url">URL and Filename safe</a> type base64
//     * encoding scheme.
//     *
//     * @return A Base64 decoder.
//     */
//    public static Base64.Decoder getUrlDecoder() {
//        return Base64.Decoder.RFC4648_URLSAFE;
//    }
//
//    /**
//     * Returns a {@link Base64.Decoder} that decodes using the
//     * <a href="#mime">MIME</a> type base64 decoding scheme.
//     *
//     * @return A Base64 decoder.
//     */
//    public static Base64.Decoder getMimeDecoder() {
//        return Base64.Decoder.RFC2045;
//    }
//
//    /**
//     * This class implements an encoder for encoding byte data using
//     * the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
//     *
//     * <p> Instances of {@link Base64.Encoder} class are safe for use by
//     * multiple concurrent threads.
//     *
//     * <p> Unless otherwise noted, passing a {@code null} argument to
//     * a method of this class will cause a
//     * {@link java.lang.NullPointerException NullPointerException} to
//     * be thrown.
//     *
//     * @see Base64.Decoder
//     * @since 1.8
//     */
//    public static class Encoder {
//
//        private final byte[] newline;
//        private final int linemax;
//        private final boolean isURL;
//        private final boolean doPadding;
//
//        private Encoder(boolean isURL, byte[] newline, int linemax, boolean doPadding) {
//            this.isURL = isURL;
//            this.newline = newline;
//            this.linemax = linemax;
//            this.doPadding = doPadding;
//        }
//
//        /**
//         * This array is a lookup table that translates 6-bit positive integer
//         * index values into their "Base64 Alphabet" equivalents as specified
//         * in "Table 1: The Base64 Alphabet" of RFC 2045 (and RFC 4648).
//         */
//        private static final char[] toBase64 = {
//                'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
//                'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
//                'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
//                'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
//                '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
//        };
//
//        /**
//         * It's the lookup table for "URL and Filename safe Base64" as specified
//         * in Table 2 of the RFC 4648, with the '+' and '/' changed to '-' and
//         * '_'. This table is used when BASE64_URL is specified.
//         */
//        private static final char[] toBase64URL = {
//                'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
//                'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
//                'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
//                'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
//                '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
//        };
//
//        private static final int MIMELINEMAX = 76;
//        private static final byte[] CRLF = new byte[]{'\r', '\n'};
//
//        static final Base64.Encoder RFC4648 = new Base64.Encoder(false, null, -1, true);
//        static final Base64.Encoder RFC4648_URLSAFE = new Base64.Encoder(true, null, -1, true);
//        static final Base64.Encoder RFC2045 = new Base64.Encoder(false, CRLF, MIMELINEMAX, true);
//
//        private final int outLength(int srclen) {
//            int len = 0;
//            if (doPadding) {
//                len = 4 * ((srclen + 2) / 3);
//            } else {
//                int n = srclen % 3;
//                len = 4 * (srclen / 3) + (n == 0 ? 0 : n + 1);
//            }
//            if (linemax > 0)                                  // line separators
//                len += (len - 1) / linemax * newline.length;
//            return len;
//        }
//
//        /**
//         * Encodes all bytes from the specified byte array into a newly-allocated
//         * byte array using the {@link Base64} encoding scheme. The returned byte
//         * array is of the length of the resulting bytes.
//         *
//         * @param src the byte array to encode
//         * @return A newly-allocated byte array containing the resulting
//         * encoded bytes.
//         */
//        public byte[] encode(byte[] src) {
//            int len = outLength(src.length);          // dst array size
//            byte[] dst = new byte[len];
//            int ret = encode0(src, 0, src.length, dst);
//            if (ret != dst.length)
//                return Arrays.copyOf(dst, ret);
//            return dst;
//        }
//
//        /**
//         * Encodes all bytes from the specified byte array using the
//         * {@link Base64} encoding scheme, writing the resulting bytes to the
//         * given output byte array, starting at offset 0.
//         *
//         * <p> It is the responsibility of the invoker of this method to make
//         * sure the output byte array {@code dst} has enough space for encoding
//         * all bytes from the input byte array. No bytes will be written to the
//         * output byte array if the output byte array is not big enough.
//         *
//         * @param src the byte array to encode
//         * @param dst the output byte array
//         * @return The number of bytes written to the output byte array
//         * @throws IllegalArgumentException if {@code dst} does not have enough
//         *                                  space for encoding all input bytes.
//         */
//        public int encode(byte[] src, byte[] dst) {
//            int len = outLength(src.length);         // dst array size
//            if (dst.length < len)
//                throw new IllegalArgumentException(
//                        "Output byte array is too small for encoding all input bytes");
//            return encode0(src, 0, src.length, dst);
//        }
//
//        /**
//         * Encodes the specified byte array into a String using the {@link Base64}
//         * encoding scheme.
//         *
//         * <p> This method first encodes all input bytes into a base64 encoded
//         * byte array and then constructs a new String by using the encoded byte
//         * array and the
//         * ISO-8859-1} charset.
//         *
//         * <p> In other words, an invocation of this method has exactly the same
//         * effect as invoking
//         * {@code new String(encode(src), StandardCharsets.ISO_8859_1)}.
//         *
//         * @param src the byte array to encode
//         * @return A String containing the resulting Base64 encoded characters
//         */
//        @SuppressWarnings("deprecation")
//        public String encodeToString(byte[] src) {
//            byte[] encoded = encode(src);
//            return new String(encoded, 0, 0, encoded.length);
//        }
//
//        /**
//         * Encodes all remaining bytes from the specified byte buffer into
//         * a newly-allocated ByteBuffer using the {@link Base64} encoding
//         * scheme.
//         * <p>
//         * Upon return, the source buffer's position will be updated to
//         * its limit; its limit will not have been changed. The returned
//         * output buffer's position will be zero and its limit will be the
//         * number of resulting encoded bytes.
//         *
//         * @param buffer the source ByteBuffer to encode
//         * @return A newly-allocated byte buffer containing the encoded bytes.
//         */
//        public ByteBuffer encode(ByteBuffer buffer) {
//            int len = outLength(buffer.remaining());
//            byte[] dst = new byte[len];
//            int ret = 0;
//            if (buffer.hasArray()) {
//                ret = encode0(buffer.array(),
//                        buffer.arrayOffset() + buffer.position(),
//                        buffer.arrayOffset() + buffer.limit(),
//                        dst);
//                buffer.position(buffer.limit());
//            } else {
//                byte[] src = new byte[buffer.remaining()];
//                buffer.get(src);
//                ret = encode0(src, 0, src.length, dst);
//            }
//            if (ret != dst.length)
//                dst = Arrays.copyOf(dst, ret);
//            return ByteBuffer.wrap(dst);
//        }
//
//        /**
//         * Wraps an output stream for encoding byte data using the {@link Base64}
//         * encoding scheme.
//         *
//         * <p> It is recommended to promptly close the returned output stream after
//         * use, during which it will flush all possible leftover bytes to the underlying
//         * output stream. Closing the returned output stream will close the underlying
//         * output stream.
//         *
//         * @param os the output stream.
//         * @return the output stream for encoding the byte data into the
//         * specified Base64 encoded format
//         */
//        public OutputStream wrap(OutputStream os) {
//            requireNonNull(os);
//            return new Base64.EncOutputStream(os, isURL ? toBase64URL : toBase64,
//                    newline, linemax, doPadding);
//        }
//
//        /**
//         * Returns an encoder instance that encodes equivalently to this one,
//         * but without adding any padding character at the end of the encoded
//         * byte data.
//         *
//         * <p> The encoding scheme of this encoder instance is unaffected by
//         * this invocation. The returned encoder instance should be used for
//         * non-padding encoding operation.
//         *
//         * @return an equivalent encoder that encodes without adding any
//         * padding character at the end
//         */
//        public Base64.Encoder withoutPadding() {
//            if (!doPadding)
//                return this;
//            return new Base64.Encoder(isURL, newline, linemax, false);
//        }
//
//        private int encode0(byte[] src, int off, int end, byte[] dst) {
//            char[] base64 = isURL ? toBase64URL : toBase64;
//            int sp = off;
//            int slen = (end - off) / 3 * 3;
//            int sl = off + slen;
//            if (linemax > 0 && slen > linemax / 4 * 3)
//                slen = linemax / 4 * 3;
//            int dp = 0;
//            while (sp < sl) {
//                int sl0 = Math.min(sp + slen, sl);
//                for (int sp0 = sp, dp0 = dp; sp0 < sl0; ) {
//                    int bits = (src[sp0++] & 0xff) << 16 |
//                            (src[sp0++] & 0xff) << 8 |
//                            (src[sp0++] & 0xff);
//                    dst[dp0++] = (byte) base64[(bits >>> 18) & 0x3f];
//                    dst[dp0++] = (byte) base64[(bits >>> 12) & 0x3f];
//                    dst[dp0++] = (byte) base64[(bits >>> 6) & 0x3f];
//                    dst[dp0++] = (byte) base64[bits & 0x3f];
//                }
//                int dlen = (sl0 - sp) / 3 * 4;
//                dp += dlen;
//                sp = sl0;
//                if (dlen == linemax && sp < end) {
//                    for (byte b : newline) {
//                        dst[dp++] = b;
//                    }
//                }
//            }
//            if (sp < end) {               // 1 or 2 leftover bytes
//                int b0 = src[sp++] & 0xff;
//                dst[dp++] = (byte) base64[b0 >> 2];
//                if (sp == end) {
//                    dst[dp++] = (byte) base64[(b0 << 4) & 0x3f];
//                    if (doPadding) {
//                        dst[dp++] = '=';
//                        dst[dp++] = '=';
//                    }
//                } else {
//                    int b1 = src[sp++] & 0xff;
//                    dst[dp++] = (byte) base64[(b0 << 4) & 0x3f | (b1 >> 4)];
//                    dst[dp++] = (byte) base64[(b1 << 2) & 0x3f];
//                    if (doPadding) {
//                        dst[dp++] = '=';
//                    }
//                }
//            }
//            return dp;
//        }
//    }
//
//    /**
//     * This class implements a decoder for decoding byte data using the
//     * Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
//     *
//     * <p> The Base64 padding character {@code '='} is accepted and
//     * interpreted as the end of the encoded byte data, but is not
//     * required. So if the final unit of the encoded byte data only has
//     * two or three Base64 characters (without the corresponding padding
//     * character(s) padded), they are decoded as if followed by padding
//     * character(s). If there is a padding character present in the
//     * final unit, the correct number of padding character(s) must be
//     * present, otherwise {@code IllegalArgumentException} (
//     * {@code IOException} when reading from a Base64 stream) is thrown
//     * during decoding.
//     *
//     * <p> Instances of {@link Base64.Decoder} class are safe for use by
//     * multiple concurrent threads.
//     *
//     * <p> Unless otherwise noted, passing a {@code null} argument to
//     * a method of this class will cause a
//     * {@link java.lang.NullPointerException NullPointerException} to
//     * be thrown.
//     *
//     * @see Base64.Encoder
//     * @since 1.8
//     */
//    public static class Decoder {
//
//        private final boolean isURL;
//        private final boolean isMIME;
//
//        private Decoder(boolean isURL, boolean isMIME) {
//            this.isURL = isURL;
//            this.isMIME = isMIME;
//        }
//
//        /**
//         * Lookup table for decoding unicode characters drawn from the
//         * "Base64 Alphabet" (as specified in Table 1 of RFC 2045) into
//         * their 6-bit positive integer equivalents.  Characters that
//         * are not in the Base64 alphabet but fall within the bounds of
//         * the array are encoded to -1.
//         */
//        private static final int[] fromBase64 = new int[256];
//
//        static {
//            Arrays.fill(fromBase64, -1);
//            for (int i = 0; i < Base64.Encoder.toBase64.length; i++)
//                fromBase64[Base64.Encoder.toBase64[i]] = i;
//            fromBase64['='] = -2;
//        }
//
//        /**
//         * Lookup table for decoding "URL and Filename safe Base64 Alphabet"
//         * as specified in Table2 of the RFC 4648.
//         */
//        private static final int[] fromBase64URL = new int[256];
//
//        static {
//            Arrays.fill(fromBase64URL, -1);
//            for (int i = 0; i < Base64.Encoder.toBase64URL.length; i++)
//                fromBase64URL[Base64.Encoder.toBase64URL[i]] = i;
//            fromBase64URL['='] = -2;
//        }
//
//        static final Base64.Decoder RFC4648 = new Base64.Decoder(false, false);
//        static final Base64.Decoder RFC4648_URLSAFE = new Base64.Decoder(true, false);
//        static final Base64.Decoder RFC2045 = new Base64.Decoder(false, true);
//
//        /**
//         * Decodes all bytes from the input byte array using the {@link Base64}
//         * encoding scheme, writing the results into a newly-allocated output
//         * byte array. The returned byte array is of the length of the resulting
//         * bytes.
//         *
//         * @param src the byte array to decode
//         * @return A newly-allocated byte array containing the decoded bytes.
//         * @throws IllegalArgumentException if {@code src} is not in valid Base64 scheme
//         */
//        public byte[] decode(byte[] src) {
//            byte[] dst = new byte[outLength(src, 0, src.length)];
//            int ret = decode0(src, 0, src.length, dst);
//            if (ret != dst.length) {
//                dst = Arrays.copyOf(dst, ret);
//            }
//            return dst;
//        }
//
//        /**
//         * Decodes a Base64 encoded String into a newly-allocated byte array
//         * using the {@link Base64} encoding scheme.
//         *
//         * <p> An invocation of this method has exactly the same effect as invoking
//         * {@code decode(src.getBytes(StandardCharsets.ISO_8859_1))}
//         *
//         * @param src the string to decode
//         * @return A newly-allocated byte array containing the decoded bytes.
//         * @throws IllegalArgumentException if {@code src} is not in valid Base64 scheme
//         */
//        public byte[] decode(String src) {
//            return decode(src.getBytes(Charset.forName("ISO_8859_1")));
//        }
//
//        /**
//         * Decodes all bytes from the input byte array using the {@link Base64}
//         * encoding scheme, writing the results into the given output byte array,
//         * starting at offset 0.
//         *
//         * <p> It is the responsibility of the invoker of this method to make
//         * sure the output byte array {@code dst} has enough space for decoding
//         * all bytes from the input byte array. No bytes will be be written to
//         * the output byte array if the output byte array is not big enough.
//         *
//         * <p> If the input byte array is not in valid Base64 encoding scheme
//         * then some bytes may have been written to the output byte array before
//         * IllegalargumentException is thrown.
//         *
//         * @param src the byte array to decode
//         * @param dst the output byte array
//         * @return The number of bytes written to the output byte array
//         * @throws IllegalArgumentException if {@code src} is not in valid Base64 scheme, or {@code dst}
//         *                                  does not have enough space for decoding all input bytes.
//         */
//        public int decode(byte[] src, byte[] dst) {
//            int len = outLength(src, 0, src.length);
//            if (dst.length < len)
//                throw new IllegalArgumentException(
//                        "Output byte array is too small for decoding all input bytes");
//            return decode0(src, 0, src.length, dst);
//        }
//
//        /**
//         * Decodes all bytes from the input byte buffer using the {@link Base64}
//         * encoding scheme, writing the results into a newly-allocated ByteBuffer.
//         *
//         * <p> Upon return, the source buffer's position will be updated to
//         * its limit; its limit will not have been changed. The returned
//         * output buffer's position will be zero and its limit will be the
//         * number of resulting decoded bytes
//         *
//         * <p> {@code IllegalArgumentException} is thrown if the input buffer
//         * is not in valid Base64 encoding scheme. The position of the input
//         * buffer will not be advanced in this case.
//         *
//         * @param buffer the ByteBuffer to decode
//         * @return A newly-allocated byte buffer containing the decoded bytes
//         * @throws IllegalArgumentException if {@code src} is not in valid Base64 scheme.
//         */
//        public ByteBuffer decode(ByteBuffer buffer) {
//            int pos0 = buffer.position();
//            try {
//                byte[] src;
//                int sp, sl;
//                if (buffer.hasArray()) {
//                    src = buffer.array();
//                    sp = buffer.arrayOffset() + buffer.position();
//                    sl = buffer.arrayOffset() + buffer.limit();
//                    buffer.position(buffer.limit());
//                } else {
//                    src = new byte[buffer.remaining()];
//                    buffer.get(src);
//                    sp = 0;
//                    sl = src.length;
//                }
//                byte[] dst = new byte[outLength(src, sp, sl)];
//                return ByteBuffer.wrap(dst, 0, decode0(src, sp, sl, dst));
//            } catch (IllegalArgumentException iae) {
//                buffer.position(pos0);
//                throw iae;
//            }
//        }
//
//        /**
//         * Returns an input stream for decoding {@link Base64} encoded byte stream.
//         *
//         * <p> The {@code read}  methods of the returned {@code InputStream} will
//         * throw {@code IOException} when reading bytes that cannot be decoded.
//         *
//         * <p> Closing the returned input stream will close the underlying
//         * input stream.
//         *
//         * @param is the input stream
//         * @return the input stream for decoding the specified Base64 encoded
//         * byte stream
//         */
//        public InputStream wrap(InputStream is) {
//            Base64.requireNonNull(is);
//            return new Base64.DecInputStream(is, isURL ? fromBase64URL : fromBase64, isMIME);
//        }
//
//        private int outLength(byte[] src, int sp, int sl) {
//            int[] base64 = isURL ? fromBase64URL : fromBase64;
//            int paddings = 0;
//            int len = sl - sp;
//            if (len == 0)
//                return 0;
//            if (len < 2) {
//                if (isMIME && base64[0] == -1)
//                    return 0;
//                throw new IllegalArgumentException(
//                        "Input byte[] should at least have 2 bytes for base64 bytes");
//            }
//            if (isMIME) {
//                // scan all bytes to fill out all non-alphabet. a performance
//                // trade-off of pre-scan or Arrays.copyOf
//                int n = 0;
//                while (sp < sl) {
//                    int b = src[sp++] & 0xff;
//                    if (b == '=') {
//                        len -= (sl - sp + 1);
//                        break;
//                    }
//                    if ((b = base64[b]) == -1)
//                        n++;
//                }
//                len -= n;
//            } else {
//                if (src[sl - 1] == '=') {
//                    paddings++;
//                    if (src[sl - 2] == '=')
//                        paddings++;
//                }
//            }
//            if (paddings == 0 && (len & 0x3) != 0)
//                paddings = 4 - (len & 0x3);
//            return 3 * ((len + 3) / 4) - paddings;
//        }
//
//        private int decode0(byte[] src, int sp, int sl, byte[] dst) {
//            int[] base64 = isURL ? fromBase64URL : fromBase64;
//            int dp = 0;
//            int bits = 0;
//            int shiftto = 18;       // pos of first byte of 4-byte atom
//            while (sp < sl) {
//                int b = src[sp++] & 0xff;
//                if ((b = base64[b]) < 0) {
//                    if (b == -2) {         // padding byte '='
//                        // =     shiftto==18 unnecessary padding
//                        // x=    shiftto==12 a dangling single x
//                        // x     to be handled together with non-padding case
//                        // xx=   shiftto==6&&sp==sl missing last =
//                        // xx=y  shiftto==6 last is not =
//                        if (shiftto == 6 && (sp == sl || src[sp++] != '=') ||
//                                shiftto == 18) {
//                            throw new IllegalArgumentException(
//                                    "Input byte array has wrong 4-byte ending unit");
//                        }
//                        break;
//                    }
//                    if (isMIME)    // skip if for rfc2045
//                        continue;
//                    else
//                        throw new IllegalArgumentException(
//                                "Illegal base64 character " +
//                                        Integer.toString(src[sp - 1], 16));
//                }
//                bits |= (b << shiftto);
//                shiftto -= 6;
//                if (shiftto < 0) {
//                    dst[dp++] = (byte) (bits >> 16);
//                    dst[dp++] = (byte) (bits >> 8);
//                    dst[dp++] = (byte) (bits);
//                    shiftto = 18;
//                    bits = 0;
//                }
//            }
//            // reached end of byte array or hit padding '=' characters.
//            if (shiftto == 6) {
//                dst[dp++] = (byte) (bits >> 16);
//            } else if (shiftto == 0) {
//                dst[dp++] = (byte) (bits >> 16);
//                dst[dp++] = (byte) (bits >> 8);
//            } else if (shiftto == 12) {
//                // dangling single "x", incorrectly encoded.
//                throw new IllegalArgumentException(
//                        "Last unit does not have enough valid bits");
//            }
//            // anything left is invalid, if is not MIME.
//            // if MIME, ignore all non-base64 character
//            while (sp < sl) {
//                if (isMIME && base64[src[sp++]] < 0)
//                    continue;
//                throw new IllegalArgumentException(
//                        "Input byte array has incorrect ending byte at " + sp);
//            }
//            return dp;
//        }
//    }
//
//    /*
//     * An output stream for encoding bytes into the Base64.
//     */
//    private static class EncOutputStream extends FilterOutputStream {
//
//        private int leftover = 0;
//        private int b0, b1, b2;
//        private boolean closed = false;
//
//        private final char[] base64;    // byte->base64 mapping
//        private final byte[] newline;   // line separator, if needed
//        private final int linemax;
//        private final boolean doPadding;// whether or not to pad
//        private int linepos = 0;
//
//        EncOutputStream(OutputStream os, char[] base64,
//                        byte[] newline, int linemax, boolean doPadding) {
//            super(os);
//            this.base64 = base64;
//            this.newline = newline;
//            this.linemax = linemax;
//            this.doPadding = doPadding;
//        }
//
//        @Override
//        public void write(int b) throws IOException {
//            byte[] buf = new byte[1];
//            buf[0] = (byte) (b & 0xff);
//            write(buf, 0, 1);
//        }
//
//        private void checkNewline() throws IOException {
//            if (linepos == linemax) {
//                out.write(newline);
//                linepos = 0;
//            }
//        }
//
//        @Override
//        public void write(byte[] b, int off, int len) throws IOException {
//            if (closed)
//                throw new IOException("Stream is closed");
//            if (off < 0 || len < 0 || off + len > b.length)
//                throw new ArrayIndexOutOfBoundsException();
//            if (len == 0)
//                return;
//            if (leftover != 0) {
//                if (leftover == 1) {
//                    b1 = b[off++] & 0xff;
//                    len--;
//                    if (len == 0) {
//                        leftover++;
//                        return;
//                    }
//                }
//                b2 = b[off++] & 0xff;
//                len--;
//                checkNewline();
//                out.write(base64[b0 >> 2]);
//                out.write(base64[(b0 << 4) & 0x3f | (b1 >> 4)]);
//                out.write(base64[(b1 << 2) & 0x3f | (b2 >> 6)]);
//                out.write(base64[b2 & 0x3f]);
//                linepos += 4;
//            }
//            int nBits24 = len / 3;
//            leftover = len - (nBits24 * 3);
//            while (nBits24-- > 0) {
//                checkNewline();
//                int bits = (b[off++] & 0xff) << 16 |
//                        (b[off++] & 0xff) << 8 |
//                        (b[off++] & 0xff);
//                out.write(base64[(bits >>> 18) & 0x3f]);
//                out.write(base64[(bits >>> 12) & 0x3f]);
//                out.write(base64[(bits >>> 6) & 0x3f]);
//                out.write(base64[bits & 0x3f]);
//                linepos += 4;
//            }
//            if (leftover == 1) {
//                b0 = b[off++] & 0xff;
//            } else if (leftover == 2) {
//                b0 = b[off++] & 0xff;
//                b1 = b[off++] & 0xff;
//            }
//        }
//
//        @Override
//        public void close() throws IOException {
//            if (!closed) {
//                closed = true;
//                if (leftover == 1) {
//                    checkNewline();
//                    out.write(base64[b0 >> 2]);
//                    out.write(base64[(b0 << 4) & 0x3f]);
//                    if (doPadding) {
//                        out.write('=');
//                        out.write('=');
//                    }
//                } else if (leftover == 2) {
//                    checkNewline();
//                    out.write(base64[b0 >> 2]);
//                    out.write(base64[(b0 << 4) & 0x3f | (b1 >> 4)]);
//                    out.write(base64[(b1 << 2) & 0x3f]);
//                    if (doPadding) {
//                        out.write('=');
//                    }
//                }
//                leftover = 0;
//                out.close();
//            }
//        }
//    }
//
//    /*
//     * An input stream for decoding Base64 bytes
//     */
//    private static class DecInputStream extends InputStream {
//
//        private final InputStream is;
//        private final boolean isMIME;
//        private final int[] base64;      // base64 -> byte mapping
//        private int bits = 0;            // 24-bit buffer for decoding
//        private int nextin = 18;         // next available "off" in "bits" for input;
//        // -> 18, 12, 6, 0
//        private int nextout = -8;        // next available "off" in "bits" for output;
//        // -> 8, 0, -8 (no byte for output)
//        private boolean eof = false;
//        private boolean closed = false;
//
//        DecInputStream(InputStream is, int[] base64, boolean isMIME) {
//            this.is = is;
//            this.base64 = base64;
//            this.isMIME = isMIME;
//        }
//
//        private byte[] sbBuf = new byte[1];
//
//        @Override
//        public int read() throws IOException {
//            return read(sbBuf, 0, 1) == -1 ? -1 : sbBuf[0] & 0xff;
//        }
//
//        @Override
//        public int read(byte[] b, int off, int len) throws IOException {
//            if (closed)
//                throw new IOException("Stream is closed");
//            if (eof && nextout < 0)    // eof and no leftover
//                return -1;
//            if (off < 0 || len < 0 || len > b.length - off)
//                throw new IndexOutOfBoundsException();
//            int oldOff = off;
//            if (nextout >= 0) {       // leftover output byte(s) in bits buf
//                do {
//                    if (len == 0)
//                        return off - oldOff;
//                    b[off++] = (byte) (bits >> nextout);
//                    len--;
//                    nextout -= 8;
//                } while (nextout >= 0);
//                bits = 0;
//            }
//            while (len > 0) {
//                int v = is.read();
//                if (v == -1) {
//                    eof = true;
//                    if (nextin != 18) {
//                        if (nextin == 12)
//                            throw new IOException("Base64 stream has one un-decoded dangling byte.");
//                        // treat ending xx/xxx without padding character legal.
//                        // same logic as v == '=' below
//                        b[off++] = (byte) (bits >> (16));
//                        len--;
//                        if (nextin == 0) {           // only one padding byte
//                            if (len == 0) {          // no enough output space
//                                bits >>= 8;          // shift to lowest byte
//                                nextout = 0;
//                            } else {
//                                b[off++] = (byte) (bits >> 8);
//                            }
//                        }
//                    }
//                    if (off == oldOff)
//                        return -1;
//                    else
//                        return off - oldOff;
//                }
//                if (v == '=') {                  // padding byte(s)
//                    // =     shiftto==18 unnecessary padding
//                    // x=    shiftto==12 dangling x, invalid unit
//                    // xx=   shiftto==6 && missing last '='
//                    // xx=y  or last is not '='
//                    if (nextin == 18 || nextin == 12 ||
//                            nextin == 6 && is.read() != '=') {
//                        throw new IOException("Illegal base64 ending sequence:" + nextin);
//                    }
//                    b[off++] = (byte) (bits >> (16));
//                    len--;
//                    if (nextin == 0) {           // only one padding byte
//                        if (len == 0) {          // no enough output space
//                            bits >>= 8;          // shift to lowest byte
//                            nextout = 0;
//                        } else {
//                            b[off++] = (byte) (bits >> 8);
//                        }
//                    }
//                    eof = true;
//                    break;
//                }
//                if ((v = base64[v]) == -1) {
//                    if (isMIME)                 // skip if for rfc2045
//                        continue;
//                    else
//                        throw new IOException("Illegal base64 character " +
//                                Integer.toString(v, 16));
//                }
//                bits |= (v << nextin);
//                if (nextin == 0) {
//                    nextin = 18;    // clear for next
//                    nextout = 16;
//                    while (nextout >= 0) {
//                        b[off++] = (byte) (bits >> nextout);
//                        len--;
//                        nextout -= 8;
//                        if (len == 0 && nextout >= 0) {  // don't clean "bits"
//                            return off - oldOff;
//                        }
//                    }
//                    bits = 0;
//                } else {
//                    nextin -= 6;
//                }
//            }
//            return off - oldOff;
//        }
//
//        @Override
//        public int available() throws IOException {
//            if (closed)
//                throw new IOException("Stream is closed");
//            return is.available();   // TBD:
//        }
//
//        @Override
//        public void close() throws IOException {
//            if (!closed) {
//                closed = true;
//                is.close();
//            }
//        }
//    }
//
//}
